Characterisation of some pharmacological effects of the venom from Vipera lebetina.

Vipera lebetina is one of the most venomous snakes on the Iran plateau. Serious clinical problems such as edema, hemorrhage and tissue necrosis are observed in humans following V. lebetina envenomating. However, little information on the pharmacological properties of the venom is available. To determine haemodynamic actions of the venom of V. lebetina, the changes in the mean arterial blood pressure of anaesthetised rats following the administration of the venom were recorded. Venom (1 mg/kg, i.v.) produced rapid cardiovascular collapse, while 0.3 mg/kg (i.v.) caused only a small transient decrease in mean arterial blood pressure. Effects of the venom on perfusion pressure in the isolated rat mesenteric bed, and on contractions of the isolated rat right atrium and the isolated guinea-pig ileum, were also studied. Exposure of the isolated rat right atrium to venom (0.1-1 mg/ml) caused a transient increase followed by a sustained reduction in the amplitude and frequency of spontaneous contractions. The transient positive inotropic and chronotropic effects were abolished when the preparation was preincubated with propranolol, but not with tolazoline. N(G)-nitro-l-arginine methyl ester pretreatment attenuated the vascular hyporeactivity to phenylephrine induced by the venom in the isolated rat mesenteric vascular bed. This suggests that nitric oxide (NO) or NO-like compounds may be present in the venom and involved in its hypotensive effect. The venom (0.3-1 mg/ml) caused concentration-dependant blockade of isolated guinea-pig ileum contractions induced by electrical field stimulation, acetylcholine or KCl. This inhibitory effect of the venom was significantly reduced by prior incubation of the venom with manoalide (1 microM) indicating involvement of a phospholipase A(2) component. Further, investigation is required to identify specific toxins responsible for the above pharmacological effects.     

新冠心苏合活血方对大鼠离体心房肌张力和心搏频率的影响

目的观察新冠心苏合活血方(简称活血方)不同浓度对大鼠离体心房肌张力和心搏频率的影响。方法取成年SD大鼠30只,断头处死后,迅速打开胸腔摘取心脏,分离并截取相连的左右心房,标本悬挂于95%氧气和5%二氧化碳饱和的Krebs-Henseleit液的浴槽中,其下端固定,上端连接张力换能器并施加一定的静息张力(0.5 g),用超级恒温槽水浴循环维持在34.5～35.5摄氏度左右,待心房可恢复自主跳动并平稳后开始进行实验;利用MS4000U-1C生物信号定量记录分析系统采集不同浓度的新冠心苏合活血方对大鼠离体心房肌张力和心搏频率的影响。结果活血方有降低大鼠离体心房肌张力和减慢心房心搏频率作用;其中200～250 mg/L浓度范围作用更明显(P<0.05,P<0.01)。结论活血方对SD大鼠离体心房肌张力和心搏频率有负性变力和负性频率作用。     

Effects of hypercholesterolaemia without ischemia on some electrophysiological and ultrastructural properties of the rabbit heart

The electrophysiological and ultrastructural alterations that occur in chronic hypercholesterolaemia were studied in isolated atria including sinoatrial (SA) and atrioventricular (AV) nodes that were obtained from rabbits subjected in 1% cholesterol diet for 18 weeks. Transmembrane action potentials were recorded simultaneously with the His bundle electrogram. The results were compared with corresponding values obtained in normal control atria. During sinus rhythm or constant atrial stimulation, the electrophysiological studies demonstrated no significant alterations of the electrical activity of the SA node, crista terminalis and AV node in preparations obtained from cholesterol-fed rabbits. Premature atrial stimulation at a critical range of coupling intervals initiated supraventricular tachycardias in $\text{7}\text{12}$ of the high cholesterol preparations but in none of the controls. Premature atrial impulses within this critical range were characterized by slow conduction through the AV node. Ultrastructural analysis of hearts obtained from cholesterol-fed rabbits revealed highly selective degenerative changes of the AV nodal cells and diffuse degeneration processes of the cardiac nerves but no obstructive coronary lesions. It was concluded that hypercholesterolaemia per se without myocardial ischemia may result in electrophysiological and ultrastructural abnormalities of the AV node and the cardiac neural tissue.     

心脏直视手术同期射频消融迷宫术治疗房颤围术期护理

目的总结心脏直视手术同期射频消融迷宫术治疗房颤围术期护理配合。方法术前积极使用血管活性药物,加强强心利尿,防止钠水潴留,维护心功能,观察心率、心律变化,教会病人作深呼吸、有效咳痰等;术后注意心电图的观察,注意有无房室传导阻滞,防止发生房室传导阻滞引起的晕厥;正确使用起搏器,识别起搏器与心电检测仪上的起搏信号;术后低心排的监测及球囊反搏的护理;出院指导,教会患者及家属准确测量脉率和脉律的方法。结果通过认真细致的术前术后护理,本组患者术后半年随访,总有效率达83%,早期疗效良好。结论做好围术期全过程的护理,是提高手术成功的重要保证。     

A Fast Region-Based Active Contour Model for Boundary Detection of Echocardiographic Images

This paper presents the boundary detection of atrium and ventricle in echocardiographic images. In case of mitral regurgitation, atrium and ventricle may get dilated. To examine this, doctors draw the boundary manually. Here the aim of this paper is to evolve the automatic boundary detection for carrying out segmentation of echocardiography images. Active contour method is selected for this purpose. There is an enhancement of Chan–Vese paper on active contours without edges. Our algorithm is based on Chan–Vese paper active contours without edges, but it is much faster than Chan–Vese model. Here we have developed a method by which it is possible to detect much faster the echocardiographic boundaries. The method is based on the region information of an image. The region-based force provides a global segmentation with variational flow robust to noise. Implementation is based on level set theory so it easy to deal with topological changes. In this paper, Newton–Raphson method is used which makes possible the fast boundary detection.     

The pathomorphological alterations of endocardial endothelium in experimental diabetes and diabetes associated with hyperlipidemia

The structural alterations of endocardial endothelial cells of the heart right atrium and left ventricle were investigated in Golden Syrian hamsters subjected to streptozotocin-induced diabetes and to a combination of diabetes and diet-induced hyperlipidemia. Animals were examined at time intervals ranging from 2 weeks to 6 months. Anionic sites of the endothelial plasmalemma were visualized by in situ perfusion of cationized ferritin. The results indicated that: (a) both atrial and ventricular endocardial endothelium are affected in streptozotocin-induced diabetes: endothelium converts from continuous into a fenestrated type, (b) although the anionic charge of the plasmalemma decreased in advanced diabetes, the newly formed fenestrae highly bound cationized ferritin, (c) combined diabetes and hyperlipidemia induced more severe alterations of endocardial endothelium: new permeable endothelial structures were formed (transendothelial channels, open intercellular junctions, fused plasmalemmal vesicles), and the cells became particularly enriched in cytoskeleton (intermediate filaments and microtubules), (d) the thick subendocardial layer of connective tissue contained, in the combined experimental model, macrophage-derived foam cells indicative for the occurrence of alterations of atherosclerotic type.     

Anatomy of the heart

The heart, enveloped in the fibrous pericardium, occupies the middle mediastinum. This article describes the essentials of external and internal cardiac anatomy, and highlights those aspects of cardiac functional anatomy that are of particular relevance to clinical cardiac examination.     

实时三平面应变率成像评价左心室不同构型原发性高血压患者左心房功能

目的 应用实时三平面应变率成像技术检测原发性高血压患者左心室重构过程中左心房功能的变化.方法 选择原发性高血压患者92例和正常对照组50名,根据Ganau分类法,将原发性高血压患者分为左心室正常构型(A组)、向心性重构型(B组)、向心性肥厚型(C组)和离心性肥厚型(D组).应用实时三平面应变率成像技术,获得左心房侧壁、下壁、前壁及后壁的应变率曲线,测量收缩期峰值应变率(S_(SR))、舒张早期峰值应变率(D_(SR))和心房收缩期峰值应变率(A_(SR)).结果 与正常对照组比较,高血压4个组S_(SR)和D_(SR)均逐渐减小(P<0.01),而A_(SR)在A组、B组和C组逐渐增大(P<0.01),在D组明显减小(P<0.01).结论 左心房功能变化发生于原发性高血压左心室重构之前;实时三平面应变率成像技术能够准确评价原发性高血压患者左心室重构进展过程中左心房功能的变化.     

家兔心房电活动的频谱分析

本文报道家兔正常心电图P波的频谱特征及损伤心房后P波频谱的变化。结果表明,正常家兔心电图P波频谱能量主要集中在1—4 Hz的低频峰段。损伤心房肌后,表现为P波变宽,频谱能量分布发生变化,1Hz的功率明显增加,而2Hz的功率明显减弱。提示 心房损伤后,P波频谱能量分布向更低频率段转移。